Mineral Nutrition - Practice Questions with Answers
77 free MCQs on Mineral Nutrition, each with its own worked answer and explanation. Essential mineral elements, their roles and deficiency symptoms. Nitrogen fixation and soil nutrition.
77 practice questions on Mineral Nutrition, sorted Easy → Hard. Try each one first, then open its answer page for the worked explanation. Want the full theory first? Read the Mineral Nutrition notes.
Atmospheric N₂ is fixed into ammonia by nitrogen-fixing bacteria (protected from oxygen by leghaemoglobin in root nodules), converted to nitrate via nitrification for plant uptake, and eventually returned to the atmosphere as N₂ via denitrification, completing the cycle.
Easy - 27 questions
Q1.
The total number of elements regarded as essential for plants is about:
What is the difference between essential and beneficial elements for plants?
A Essential and beneficial elements are sometimes mistakenly described as the exact same group of plant nutrients under two different historical names in general practice
B Essential elements are required by all plants and have specific metabolic roles; beneficial elements improve growth in some plants but are not universally required
C Beneficial elements are sometimes thought to become essential to plant survival mainly at unusually high soil concentrations as frequently described in most textbook accounts
D Essential elements are sometimes thought to be obtained by plants mainly from atmospheric gases absorbed through the stomata during normal conditions as generally observed
What is the biochemical basis of nitrogen fixation by nitrogenase? Include the role of ferredoxin.
A Nitrogenase is sometimes reported to directly oxidize atmospheric N<sub>2</sub> gas using molecular oxygen as the terminal electron acceptor in this overall reaction as frequently observed in practice
B Ferredoxin (reduced by photosynthesis or respiration) donates electrons to dinitrogenase reductase (Fe protein) which then reduces dinitrogenase (MoFe protein) that reduces N<sub>2</sub> to NH<sub>3</sub>
C Nitrogenase is sometimes reported to function mainly under strongly alkaline soil conditions above pH 9, rarely in neutral or acidic soils in many documented cases according to conventional understanding
D N<sub>2</sub> is sometimes thought to be fixed through a single-step direct reduction reaction that generally uses ordinary water molecules as the sole electron source in routine practice
What is the GS-GOGAT pathway for nitrogen assimilation in plants?
A Glutamine-GOGAT: atmospheric N<sub>2</sub> gas is sometimes thought to be incorporated directly into glutamate without any prior reduction step occurring
B Glutamine synthetase (GS) incorporates NH4+ into glutamine; GOGAT transfers the amide group to alpha-ketoglutarate, forming two glutamates
C GS first degrades existing glutamate into free ammonia; GOGAT then reassembles it back into glutamine molecules afterward
D This pathway is sometimes thought to operate mainly within leaf mesophyll cells and rarely elsewhere in the entire plant body
How do carnivorous plants digest their prey and what nutrients do they gain?
A They rely on passive decomposition by ambient soil microbes to break down trapped insects, slowly releasing trace minerals the plant then absorbs over several weeks
B They secrete protease and other hydrolytic enzymes to digest prey, primarily gaining nitrogen and phosphorus to supplement growth in nutrient-poor environments
C They absorb potassium and other cations released by their prey, though this contributes relatively little toward meeting their overall nitrogen requirements
D They mechanically trap and crush their prey using specialized leaf structures, with most nutrient absorption happening afterward through the root system
What is luxury consumption of minerals in plants and why can it be harmful?
A Plants regulate mineral uptake so closely and consistently that the amount absorbed matches the amount required for optimal growth across most soil and seasonal conditions
B Plants absorb minerals in excess of what is needed for optimal growth when soil levels are high; excess can disrupt ion balance and cause toxicity
C Plants actively exclude most mineral ions beyond their immediate metabolic needs through selective root membrane transport
D Luxury consumption of minerals tends to improve overall plant growth rate and final crop yield in most field conditions
What is Hoagland solution and what is its importance in plant nutrition research?
A A naturally occurring soil extract that researchers collect, filter, and dilute before applying it to hydroponic growing systems
B A defined nutrient solution containing all essential minerals in known concentrations, used to study mineral requirements and grow plants without soil
C A pesticide and fungicide blend regularly applied to hydroponically grown plants to protect their developing root systems from insect pests and fungal infection
D A hormone-supplemented growth medium developed mainly for propagating plant tissue cultures under sterile laboratory conditions
How does silicon benefit plant growth even though it is not universally essential?
A Silicon is sometimes reported to provide little measurable physiological, structural, or defensive benefit to any plant species studied so far overall in most cases
B Silicon deposits in cell walls increase rigidity and pest resistance, improve water use efficiency, and reduce toxic metal stress; essential for rice and other grasses
C Silicon is sometimes said to directly enhance the rate of biological nitrogen fixation occurring specifically within legume root nodules each season under typical conditions
D Silicon is sometimes reported to directly increase the rate of carbon fixation occurring during the Calvin cycle stage according to standard textbooks in general practice
What is the Haber-Bosch process and how does it compare to biological nitrogen fixation?
A Haber-Bosch is described, incorrectly, as a naturally occurring biological process performed mainly by free-living nitrogen-fixing soil bacteria found in agricultural fields worldwide as frequently described
B Haber-Bosch is an industrial process (N<sub>2</sub> + H<sub>2</sub> at high T/P with Fe catalyst) that produces ammonia; it requires 400-500 degrees C and 200 atm; biological fixation occurs at room temperature using nitrogenase
C The Haber-Bosch reaction is incorrectly reported to take place naturally within the specialized root nodules formed by leguminous host plants in most textbook accounts during normal conditions as generally observed
D Biological nitrogen fixation is said to consume far more total industrial energy overall than the Haber-Bosch process itself ever requires under any conditions in typical laboratory settings under usual circumstances
What is phytoremediation and which plants are used for it?
A Using living plants as a biological raw material source for manufacturing commercial chemical fertilizers on a large scale according to most researchers
B Using plants to absorb and accumulate toxic heavy metals from contaminated soils (hyperaccumulators like Thlaspi, Alyssum, sunflower) to clean up pollution
C Using plants mainly to fix atmospheric nitrogen gas directly into the surrounding contaminated soil over time in the majority of cases studied as widely reported
D Growing plants in contaminated soil mainly to physically prevent surface erosion, with little decontamination effect noted in standard practice under most conditions encountered
What is the role of chloride ions (Cl-) in plant physiology?
A Chloride ions are sometimes reported to be largely non-essential and to play little measurable physiological role in most plant species studied as frequently observed in practice
B Chloride is a micronutrient essential for photosynthesis (water-splitting in PSII), stomatal regulation (counter-ion for K+ in guard cells), and osmoregulation
C Chloride is sometimes said to function chiefly as a macronutrient required mainly for cross-linking pectin molecules within plant cell walls broadly in many documented cases
D Chloride is sometimes reported to play a meaningful physiological role mainly within salt-tolerant halophyte plant species, rarely elsewhere according to conventional understanding
How does pH of the soil affect nutrient availability to plants?
A Soil pH is sometimes reported to exert little measurable effect on the solubility or overall availability of soil nutrients in most cases in routine practice overall in most cases
B Soil pH dramatically affects nutrient solubility: most nutrients are available at pH 6-7; iron and manganese become insoluble above pH 7; aluminum and manganese become toxic below pH 5
C Soil pH is sometimes said to influence mainly the availability of nitrogen alone, with little effect on any other soil nutrient present under typical conditions according to standard textbooks
D Mineral deficiencies are sometimes reported to arise mainly within acidic soils, and are said to rarely occur within alkaline soils generally in general practice as frequently described
What is the difference between ectomycorrhizae and arbuscular mycorrhizae?
A Both fungal types are sometimes reported to penetrate root cortical cells in a largely identical structural manner, with little meaningful difference between them in most textbook accounts during normal conditions
B Ectomycorrhizae form a sheath around roots and penetrate between cortical cells (Hartig net) but not into cells; arbuscular mycorrhizae penetrate into cortical cells forming arbuscules (tree-like structures)
C Ectomycorrhizae are described as being associated mainly with agricultural crop plants in general; arbuscular mycorrhizae mainly with large forest trees instead as generally observed in typical laboratory settings
D Arbuscular mycorrhizae are sometimes said to form a largely parasitic, mostly non-mutualistic relationship with their host plant in many documented cases under usual circumstances according to most researchers